CNN political commentator Carl Bernstein has fired an explosive broadside at President Trump, claiming former National Security Adviser John Bolton’s departure from the administration is the latest evidence that Trump “cannot conduct a coherent presidency.”

“This is, perhaps, the most convincing evidence that we’ve seen of late that we have a governing crisis under this president — a dire crisis in which the national security of the United States is not secure because of the conduct of the president of the United States,” Bernstein said on Tuesday.

His comments came after the president announced on Twitter that he Bolton was leaving his job. Bolton is the third national security adviser to exit the administration.